Lipid Accumulation and Biodiesel Production from Filamentous Cyanobacteria Native to Pakistan.

Depleting fossil fuel resources and increasing energy demand have intensified the emphasis on biofuel production cyanobacteria. In this study, 19 cyanobacterial filamentous strains were isolated from various regions of Pakistan, including the northern areas and the University of the Punjab, Lahore. Sudan black, Nile red, and BODIPY staining, together with CLSM, fluorimetry, FTIR, growth in different nitrate concentrations, and GC techniques, were used to confirm and measure the lipid and diesel contents within isolated cyanobacterial filaments. Oscillatoria sp. strain CFF-6 showed a significantly higher yield (biodiesel/ biomass=35.6%). Leptolyngbya sp. strain CFF-18 showed a higher yield (biodiesel/biomass=17.1%) compared to other Leptolyngbya strains. FAME (Fatty Acid Methyl Ester) analysis was also performed. Oscillatoria are better biodiesel producers in comparison to other filamentous strains.

Exploring Corymbia torelliana hydrochar combustion kinetics through thermogravimetric analysis, peak deconvolution and reaction profile modelling.

This study aims to conduct an applied and innovative investigation to enhance the energy quality of wood residues through hydrothermal carbonization pretreatment. For this purpose, the treatment was carried out at three different temperatures: 180, 220, and 240 °C under autogenous pressure. The in natura material and the hydrochars were characterized, and thermogravimetric analyses were performed in an O2 atmosphere with heating rates of 2.5, 5, 10, and 20 °C min-1. The global activation energy for natura biomass combustion was determined to be 112.49 kJ.mol-1. On the other hand, the hydrothermal carbonization process promoted a reduction in this value for the 94.85 kJ.mol-1. The conversion function for the in natura biomass was characterized as 1 - α , order 1, while the hydrochars was 2(1-α) [-ln(1-α)] (1/2), Avrami-Erofe'ev I. Triple kinetic parameters were ascertained, and the conversion curves along with their respective derivatives were modeled, exhibiting minimal deviations between theoretical and experimental data. This facilitated the mathematical representation of the reaction processes and allowed for a comprehensive comparison of the results.

Cytotoxicity and Epithelial Barrier Toxicity of Fine Particles from Residential Biomass Pellet Burning.

Rising environmental concerns associated with the domestic use of solid biofuels have driven the search for clean energy alternatives. This study investigated the in vitro toxicological characteristics of PM2.5 emissions from residential biomass pellet burning using the A549 epithelial cell line. The potential of modern pellet applications to reduce PM2.5 emissions was evaluated by considering both mass reduction and toxicity modification. PM2.5 emissions from raw and pelletized biomass combustion reduced cell viability, indicative of acute toxicity, and also protein expression associated with epithelial barrier integrity, implying further systemic toxicity, potentially via an oxidative stress mechanism. Toxicity varied between PM2.5 emissions from raw biomass and pellets, with pelletized straw and wood inducing cytotoxicity by factors of 0.54 and 1.30, and causing epithelial barrier damage by factors of 1.76 and 2.08, respectively, compared to their raw counterparts. Factoring in both mass reduction and toxicity modifications, PM2.5 emissions from pelletized straw and wood dropped to 1.83 and 5.07 g/kg, respectively, from 30.1 to 9.32 g/kg for raw biomass combustion. This study underscores the effectiveness of pelletized biomass, particularly straw pellets, as a sustainable alternative to traditional biofuels and highlights the necessity of considering changes in toxicity when assessing the potential of clean fuels to mitigate emissions of the PM2.5 complex.

Effect of NH4Cl supplementation on growth, photosynthesis, and triacylglycerol content in Chlamydomonas reinhardtii under mixotrophic cultivation.

AIM: Ammonium chloride (NH4Cl) is one of the nitrogen sources for microalgal cultivation. An excessive amounts of NH4Cl are toxic for microalgae. However, combining mixotrophic conditions and excessive quantities of NH4Cl positively affects microalgal biomass and lipid production. In this study, we investigated the impact of NH4Cl on the growth, biomass, and triglyceride (TAG) content of the green microalga Chlamydomonas reinhardtii especially under mixotrophic conditions. METHODS AND RESULTS: Under photoautotrophic conditions (without organic carbon supplementation), adding 25 mM NH4Cl had no significant effect on microalgal growth or TAG content. However, under mixotrophic condition (with acetate supplementation), NH4Cl interfered with microalgal growth while inducing TAG content. To explore these effects further, we conducted a two-step cultivation process and found that NH4Cl reduced microalgal growth, but induced total lipid and TAG content, especially after 4-day cultivation. The photosynthesis performances showed that NH4Cl completely inhibited oxygen evolution on day 4. However, NH4Cl slightly reduced the Fv/Fm ratio indicating that the NH4Cl supplementation directly affects microalgal photosynthesis. To investigate the TAG induction effect by NH4Cl, we compared the protein expression profiles of microalgae grown mixotrophically with and without 25 mM NH4Cl using a proteomics approach. This analysis identified 1782 proteins, with putative acetate uptake transporter GFY5 and acyl-coenzyme A oxidase being overexpressed in the NH4Cl-treated group. CONCLUSION: These findings suggested that NH4Cl supplementation may stimulate acetate utilization and fatty acid synthesis pathways in microalgae cells. Our study indicated that NH4Cl supplementation can induce microalgal biomass and lipid production, particularly when combined with mixotrophic conditions.

Efficient utilization of xylose requires CO2 fixation in Synechococcus elongatus PCC 7942.

Cyanobacteria show great promise as autotrophic hosts for the renewable biosynthesis of useful chemicals from CO2 and light. While they can efficiently fix CO2, cyanobacteria are generally outperformed by heterotrophic production hosts in terms of productivity and titer. Photomixotrophy, or co-utilization of sugars and CO2 as carbon feedstocks, has been implemented in cyanobacteria to greatly improve productivity and titers of several chemical products. We introduced xylose photomixotrophy to a 2,3-butanediol producing strain of Synechococcus elongatus PCC 7942 and characterized the effect of gene knockouts, changing pathway expression levels, and changing growth conditions on chemical production. Interestingly, 2,3-butanediol production was almost completely inhibited in the absence of added CO2. Untargeted metabolomics implied that RuBisCO was a significant bottleneck, especially at ambient CO2 levels, restricting the supply of lower glycolysis metabolites needed for 2,3-butanediol production. The dependence of the strain on elevated CO2 levels suggests some practical limitations on how xylose photomixotrophy can be efficiently carried out in S. elongatus.

Energy transition in sustainable transport: concepts, policies, and methodologies.

The growth in population, economic expansion, and urban dynamism has collectively driven a surge in the use of public and private transport, resulting in increased energy consumption in this sector. Consequently, the transport sector requires an energy transition to meet mobility demands, foster economic growth, and achieve emission reduction. The main objective of this article is to systematically review the literature on energy transition in transportation, categorizing research, identifying barriers, and providing analysis to guide future steps, with a special focus on developing countries. The methodology used in this study follows a sequence for a systematic review based on an evidence-informed approach and specific guidelines for systematic reviews, exploring the concepts, methodologies, and policies within the context of the energy transition, considering transport modes and geographical scope. The findings indicate that electricity is the predominant energy source in this transition, although its prevalence varies by transport mode. Biofuels present an alternative, primarily contributing to emission reduction associated with fossil fuel use. Natural gas emerges as a cost-effective option for heavy transport, while hydrogen represents another alternative, with the challenge of developing recharging infrastructure. Determinants of this transition include recharging infrastructure, tax and nontax incentives, public policies, the generation of electric power from renewable sources, and the management of battery life cycles from mineral extraction to disposal.

Enhancing microalgae-based biofuels production, wastewater treatment and bio-products generation by synergistic effect of iron and zinc addition to real municipal wastewater.

The feasibility of microalgae-based biofuel production is still unclear due to the high cost and energy consumption. In order to be competitive with traditional fuels, the price per unit biofuel produced should be reduced by improving microalgal cells quality for higher biofuels productivity as well as enhancing microalgae other advantages such as wastewater treatment (WWT) and CO2 bio-fixation. In this research, the synergistic effect of iron (Fe) and zinc (Zn) addition to municipal wastewater (MWW) on Chlorella sorokiniana Pa.91 performance was investigated in terms of biomass productivity, WWT, bio-products generation and biofuel quality. According to the result, maximum biomass concentration of 1.1, 1.49, 1.36 and 1.9 mg/L were achieved after 10 days C. sorokiniana cultivation in MWW before and after addition of Fe (9 mg/L), Zn (1 mg/L) and combined Zn/Fe (6/0.5 mg/L), respectively. It was observed that the nutrients uptake ability of microalgal cells improved by pre-treatment with Fe/Zn, as the mass balance of COD, NH4 and PO43- increased from 104.5, 13.6 and 2.9 to 111.6, 16.6 and 3.78 mg per 1 g C. sorokiniana, respectively. By adding Fe/Zn, the lipid content increased from 25 to 33 % CDW, while, no significant changes were observed in the protein and carbohydrate content. The results revealed that the fatty acid composition (i.e. SFA and MUFA content) and biofuel quality of C. sorokiniana remarkability enhanced after Fe/Zn supplementation. Overall, our finding suggested that MWW enrichment with combined Fe and Zn at an appropriate dosage is a promising approach for improving microalgae performance in particular increasing biofuel production quantity and quality.

Sustainable algal biorefinery: A review on current perspective on technical maturity, supply infrastructure, business and industrial opportunities.

The environmental problems associated with the use of fossil fuels demand a transition to renewable sources for fuels and energy. A biorefinery approach has often been considered and microalgae as a feedstock has been pampered for its numerous possibilities to produce biofuels. Depending on the species and cultivation conditions, microalgae can produce fats, proteins and sugars. These raw materials can thus be utilized in the production of biofuels, bioenergy and biochemicals. For this reason, algal biofuels are considered as sustainable and renewable options for climate related challenges. However, there are many issues such as supply infrastructure, business and refinery opportunities, as well as their efficacy, tied to sustainable production of these energetic materials from algae. Thus, technical maturity, scalability, energy and material balance demands coupled with cost, nutrient resources demand, certification and legislation are needed to demonstrate the biorefinery opportunities of algal biomass valorisation. This paper therefore recommends that various consortiums tasked with algal biofuel projects should be chosen for a more holistic integrated multidisciplinary approach to address the advancement of algal biofuel technology.

Hydrothermal conditioning of oleaginous yeast cells to enable recovery of lipids as potential drop-in fuel precursors.

BACKGROUND: Lipids produced using oleaginous yeast cells are an emerging feedstock to manufacture commercially valuable oleochemicals ranging from pharmaceuticals to lipid-derived biofuels. Production of biofuels using oleaginous yeast is a multistep procedure that requires yeast cultivation and harvesting, lipid recovery, and conversion of the lipids to biofuels. The quantitative recovery of the total intracellular lipid from the yeast cells is a critical step during the development of a bioprocess. Their rigid cell walls often make them resistant to lysis. The existing methods include mechanical, chemical, biological and thermochemical lysis of yeast cell walls followed by solvent extraction. In this study, an aqueous thermal pretreatment was explored as a method for lysing the cell wall of the oleaginous yeast Rhodotorula toruloides for lipid recovery. RESULTS: Hydrothermal pretreatment for 60 min at 121 °C with a dry cell weight of 7% (w/v) in the yeast slurry led to a recovery of 84.6 ± 3.2% (w/w) of the total lipids when extracted with organic solvents. The conventional sonication and acid-assisted thermal cell lysis led to a lipid recovery yield of 99.8 ± 0.03% (w/w) and 109.5 ± 1.9% (w/w), respectively. The fatty acid profiles of the hydrothermally pretreated cells and freeze-dried control were similar, suggesting that the thermal lysis of the cells did not degrade the lipids. CONCLUSION: This work demonstrates that hydrothermal pretreatment of yeast cell slurry at 121 °C for 60 min is a robust and sustainable method for cell conditioning to extract intracellular microbial lipids for biofuel production and provides a baseline for further scale-up and process integration.

Use of Residual Lignocellulosic Biomass and Algal Biomass to Produce Biofuels.

Efforts are intensifying to identify new biofuel sources in response to the pressing need to mitigate environmental pollutants, such as greenhouse gases, which are key contributors to global warming and various worldwide calamities. Algae and microalgae present themselves as excellent alternatives for solid-gaseous fuel production, given their renewable nature and non-polluting characteristics. However, making biomass production from these organisms economically feasible remains a challenge. This article collates various studies on the use of lignocellulosic waste, transforming it from environmental waste to valuable organic supplements for algae and microalgae cultivation. The focus is on enhancing biomass production and the metabolites derived from these biomasses.

Worldwide developments and challenges for solar pyrolysis.

The solar pyrolysis of materials has emerged as a promising technology for their efficient conversion into solid char, syngas and oil. The technology has its challenges, however, as constraints such as solar intermittence and scalability must be overcame for solar pyrolysis to thrive. The present work presents a review of the developments in solar pyrolysis considering a such as development by country, solar technology employed, etcetera. Moreover, details on the challenges and potential future developments are presented. It was found that most of the development in solar pyrolysis has been focused on waste-handling, and that a particular challenge exists in an adequate control system to achieve the desired end products.

Role of microbial laccases in valorization of lignocellulosic biomass to bioethanol.

The persistent expansion in world energy and synthetic compounds requires the improvement of renewable alternatives in contrast to non-sustainable energy wellsprings. Lignocellulose is an encouraging feedstock to be utilized in biorefineries for its conversion into value-added products, including biomaterials, biofuels and several bio-based synthetic compounds. Aside from all categories, biofuel, particularly bioethanol is the most substantial fuel derived from lignocellulosic biomass and can be obtained through microbial fermentation. Generally, extreme settings are required for lignocellulosic pretreatment which results in the formation of inhibitors during biomassdegradation. Occasionally, lignin polymers also act as inhibitors and are left untreated during the pretreatment, engendering inefficient hydrolysis. The valorization of lignocellulosic biomass by laccases can be viewed as a fundamental trend for improving bioethanol production. However, one of the main obstacles for developing commercially viable biofuel industries is the cost of enzymes, which can be resolved by utilizing laccases derived from microbial sources. Microbial laccases have been considered an exceptionally integral asset for delignification and detoxification of pretreated LCB, which amplify the resultant fermentation and saccharification processes. This review provides a summary of microbial laccases and their role in valorizing LCB to bioethanol, compelling enthralling applications in bio-refining industries all across the globe.

Life cycle analysis of apple pomace biorefining for biofuel and pectin production.

This study investigated the environmental impacts associated with converting apple pomace, a globally abundant resource, into biofuels and high-value products using a comparative consequential life cycle assessment. In three developed scenarios, an acid pretreatment method was applied and the pretreated liquid was used for ethanol and pectin production. The pretreated solids were utilized to produce different products: scenario 1 produced biogas, scenario 2 generated butanol, and scenario 3 yielded both biogas and butanol from the solids. The results demonstrated that scenario 1 exhibited the best performance compared to the other two scenarios, imposing the lowest environmental burdens across all damage categories, including human health, ecosystems, and resources. Despite the induced impacts, the benefits of avoided products, i.e., ethanol, natural gas, butanol, acetone, and pectin, compensated for these induced environmental impacts to some extent. The results also revealed that among all products generated through the biorefineries, first-generation ethanol substitution had the most significant positive environmental impacts. Overall, the biorefinery developed in scenario 1 represents the most feasible strategy for a circular bioeconomy. It performs 84.38 % and 72.98 % better than scenarios 2 and 3 in terms of human health, 85.34 % and 74.54 % better in terms of ecosystems, and more than 100 % better in terms of resources. Conversely, scenario 2 resulted in the highest net impacts across all damage categories. Furthermore, in scenario 1, the midpoint results showed 83.10 % and 71.08 % lower impacts on global warming, 85.15 % and 74.17 % lower impacts on terrestrial acidification, and 99.26 % and 98.53 % lower impacts on fossil resource scarcity compared to scenarios 2 and 3, respectively. In conclusion, the first scenario shows promise for the sustainable valorization of apple pomace.

Soybean molasses can be used as a substitute for corn in grazing beef cattle supplements during the rainy season.

Soybean molasses (SBMO) is a byproduct derived from the production of soy protein concentrate, obtained through solubilization in water and alcohol. The utilization of SBMO as an animal feed ingredient shows promising potential, primarily due to its low cost and as a potential energy concentrate. This study aimed to assess the intake, digestibility, ruminal parameters (pH and ruminal ammonia - NH3), nitrogen retention (NR) and microbial protein synthesis in grazing beef cattle supplemented with SBMO as a substitute for corn during the rainy season. Five Nellore (10-month-old) bulls with an average initial weight of 246 ± 11.2 kg were utilized in a 5 × 5 Latin square design. The animals were housed in five paddocks, each consisting of 0.34 ha of Marandu grass (Urochloa brizantha). Five isonitrogenous protein-energy supplements (300 g crude protein [CP]/kg supplement) were formulated, with SBMO replacing corn at varying levels (0, 0.25, 0.50, 0.75, or 1.00 g-1 g). The supplements were provided daily at a quantity of 2.0 kg-1 animal. The inclusion of SBMO at any level of corn substitution did not significantly affect the intake of pasture dry matter or total dry matter (P > 0.10). Likewise, the intake of CP and, consequently, the ruminal concentration of NH3 did not differ among the SBMO levels. Increasing the inclusion of SBMO did not have a significant impact on NR (P > 0.10), indicating that animals receiving supplements containing 100% SBMO as a substitute for corn may perform similarly to animals receiving supplements with 100% corn (0% SBMO). Soybean molasses represents a viable alternative energy source for grazing beef cattle during the rainy season and can entirely replace corn without adversely affecting animal nutritional performance.

The role of AdhE on ethanol tolerance and production in Clostridium thermocellum.

Many anaerobic microorganisms use the bifunctional aldehyde and alcohol dehydrogenase enzyme, AdhE, to produce ethanol. One such organism is Clostridium thermocellum, which is of interest for cellulosic biofuel production. In the course of engineering this organism for improved ethanol tolerance and production, we observed that AdhE was a frequent target of mutations. Here, we characterized those mutations to understand their effects on enzymatic activity, as well ethanol tolerance and product formation in the organism. We found that there is a strong correlation between NADH-linked alcohol dehydrogenase (ADH) activity and ethanol tolerance. Mutations that decrease NADH-linked ADH activity increase ethanol tolerance; correspondingly, mutations that increase NADH-linked ADH activity decrease ethanol tolerance. We also found that the magnitude of ADH activity did not play a significant role in determining ethanol titer. Increasing ADH activity had no effect on ethanol titer. Reducing ADH activity had indeterminate effects on ethanol titer, sometimes increasing and sometimes decreasing it. Finally, this study shows that the cofactor specificity of ADH activity was found to be the primary factor affecting ethanol yield. We expect that these results will inform efforts to use AdhE enzymes in metabolic engineering approaches.

Biobutanol production from underutilized substrates using Clostridium: Unlocking untapped potential for sustainable energy development.

The increasing demand for sustainable energy has brought biobutanol as a potential substitute for fossil fuels. The Clostridium genus is deemed essential for biobutanol synthesis due to its capability to utilize various substrates. However, challenges in maintaining fermentation continuity and achieving commercialization persist due to existing barriers, including butanol toxicity to Clostridium, low substrate utilization rates, and high production costs. Proper substrate selection significantly impacts fermentation efficiency, final product quality, and economic feasibility in Clostridium biobutanol production. This review examines underutilized substrates for biobutanol production by Clostridium, which offer opportunities for environmental sustainability and a green economy. Extensive research on Clostridium, focusing on strain development and genetic engineering, is essential to enhance biobutanol production. Additionally, critical suggestions for optimizing substrate selection to enhance Clostridium biobutanol production efficiency are also provided in this review. In the future, cost reduction and advancements in biotechnology may make biobutanol a viable alternative to fossil fuels.

State-of-the-art review on hydrogen's production, storage, and potential as a future transportation fuel.

Global energy consumption is expected to reach 911 BTU by the end of 2050 as a result of rapid urbanization and industrialization. Hydrogen is increasingly recognized as a clean and reliable energy vector for decarbonization and defossilization across various sectors. Projections indicate a significant rise in global demand for hydrogen, underscoring the need for sustainable production, efficient storage, and utilization. In this state-of-the-art review, we explore hydrogen production methods, compare their environmental impacts through life cycle analysis, delve into geological storage options, and discuss hydrogen's potential as a future transportation fuel. Combining electrolysis to make hydrogen and storing it in porous underground materials like salt caverns and geological reservoirs looks like a good way to balance out the variable supply of renewable energy and meet the demand at peak times. Hydrogen is a key component of our sustainable economy, and this article gives a broad overview of the process from production to consumption, touching on technical, economic, and environmental concerns along the way. We have made an attempt in this paper to compile different methods for the production of hydrogen and its storage, the challenges faced by current methods in the manufacturing of hydrogen gas, and the role of hydrogen in the future. This review paper will serve as a very good reference for hydrogen system engineering applications. The paper concludes with some suggestions for future research to help improve the technological efficiency of certain production methods, all with the goal of scaling up the hydrogen economy.

Upgrade of Acetone-Butanol-Ethanol Mixture to High-Value Biofuels over Ca-Doped Ni-CaO-SiO2 catalyst.

The selective conversion of biomass fermentation derived from an acetone-butanol-ethanol (ABE) mixture into high-value biofuels is of paramount importance for industrial applications. However, challenges persist in effectively controlling the selectivity of long carbon chain ketones in elevated ABE conversion. In this research, a Ca-doped Ni-CaO-SiO2 catalyst was designed and employed to achieve a remarkable conversion of 89.9% into ketone products from the extracted ABE mixture. The selectivity for C8+ ketones reaches 41.8%, demonstrating exceptional performance. The reversible phase transition between Ca2SiO4 and CaCO3 enhances the recyclability, thereby improving the sustainability of the process. Additionally, the trace intermediate 3-hepten-2-one was successfully detected using two-dimensional GC×GC-MS, elucidating the conversion pathway in the catalytic upgrading of the ABE mixture. This finding offers a potential route for the efficient utilization of biomass and the highly selective production of value-added chemicals.

Role of natural resources, renewable energy sources, eco-innovation and carbon taxes in carbon neutrality: Evidence from G7 economies.

Global warming has created problems for human life, and it has been increasing for a few years. All the developing and developed countries are establishing policies to attain zero carbon status. This study extends the ongoing debate on carbon emissions. It examines the effect of natural resources and RE (Biofuel and other renewable sources) on greenhouse gas (CO2 emission and PM2.5) emissions while using data over 22 years (1999-2021) from G7 countries. In addition, this study has investigated the effect of carbon taxes, financial development, and environmental policies on carbon neutrality. The cross-sectional-ARDL, the Common correlated effect means group (CCEMG), and the Augmented mean group (AMG) cutting-edge model have been employed. Quantile regression has been employed for robustness. The study results demonstrate that biofuel and other renewable energy (RE) sources, carbon taxes, environmental policy, and eco-innovation decrease greenhouse gas emissions (CO2 emissions). Meanwhile, financial development, and natural resource dependence positively impact carbon neutrality. The robustness result also verifies the findings from CS-ARDL, AMG, and CCEMG methods. The empirical findings are used to infer policy implications for G7 economies.